Answer and Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Compounds are made up of two or more elements which are chemically bonded. The elements and the properties of the compound are different. Exposure to light and chemical reaction can break compounds into elements. Compounds are only chemically separated not physically. The mass of elements determined the mass of the compound.
To be injured by an animal with poisonous spines, you must: be the aggressor and touch the animal first.
<h3>What is the use of spines in animals?</h3>
- Spines are hard, needle-like anatomical structures found in both vertebrate and invertebrate species.
- The spines of most spiny mammals are modified hairs, with a spongy center covered in a thick, hard layer of keratin and a sharp tip.
- Spines on an animal’s body help defend it.
- They can be irritating or painful, or difficult to swallow.
- Spines are also important tools for communication, shock absorption, and rain protection.
- Animals like porcupine shoot their spines (quills) for defense. Some spines can also pass through gloves.
- To prevent attacked by an animal with poisonous spines you must remain calm and observe your surroundings.
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Some plants reproduce asexually by natural occurring forces, such as wind and water carrying away their seeds.
